Samwise posted a picture one can only imagine is N'zoth the God of the Deep.
Hearthstone N'zoth
Cthulhu
Then Kul'Tiras armor was datamined. A naval Human Kingdom that has been absent since Grand Admiral Daelin Proudmoore was killed back in WCIII
Expect Kul'Tiras to become a paradory of Innsmouth. Twlight Cult might have a firm grip on Kul'Tiras or simply enthralled them with the power of the Sea God and his Demi-Goddess Queen Azshara. expect some form of Deep Ones to be represented.
Next expansion is going to be dark and nightmarish indeed I believe. Gonna have to do something significant to keep the story flowing hard after the significant climax 7.3.5 provides.